This is a simple and physically sensible way to look at the climate effects of different energy system transitions. (thinkprogress.org)
Strength athletes use different energy systems when training and the data is not comparable. (fitnessandpower.com)
Historically, a major drawback to the use and cost - effectiveness of alternative energy systems has been that they are too variable — if the wind doesn't blow or the sun doesn't shine, a completely different energy system has to be available to pick up the slack. (sciencedaily.com)